Editors' ChoiceMelanoma

Measuring Metastatic Melanoma's Risk

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Science Translational Medicine  09 Dec 2009:
Vol. 1, Issue 10, pp. 10ec38
DOI: 10.1126/scitranslmed.3000683

Melanoma—which accounts for only a small fraction of skin cancer cases—causes more deaths than any other skin disease. Patients with stage IV melanoma, in which the cancer has spread to other organs—the lung and brain are common—usually survive less than one year. Some patients, however, live longer after the disease has metastasized, and it is not clear what is different about these individuals. Melanoma is usually staged by using a "TNM" system, with the "T" category indicating tumor thickness, "N" indicating spread to nearby lymph nodes, and "M" for metastasis. The ability to classify metastatic tumors further to predict patient survival more accurately would be useful, potentially aiding treatment decisions and the development of new therapies. To that end, Bogunovic et al. examined gene expression profiles in metastatic melanoma samples, looking for genes with different levels of expression in patients who survived longer than 1.5 years as compared to those who did not. Samples from the longer-lived patients showed more expression of genes that encode proteins used in the immune system—T cell–associated proteins and chemokines, for example—and decreased expression of genes related to cell proliferation. The scientists also examined several other parameters and found that a lower mitotic index—the fraction of cells undergoing cell division—was likewise associated with longer survival. With the gene expression profile and the mitotic index from each patient in hand, the researchers were better able to predict survival than they were with the TNM system alone. Furthermore, their analysis suggests that enhanced immune surveillance plays a role in the improved survival of some patients with metastatic melanoma.

D. Bogunovic et al., Immune profile and mitotic index of metastatic melanoma lesions enhance clinical staging in predicting patient survival. Proc. Natl. Acad. Sci. U.S.A. 106, 20429–20434 (2009). [Abstract]

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